A Comparison Between 4.0 mm Stainless Steel and 4.75 mm Titanium Single-rod Systems for Anterior Thoracoscopic Spinal Fusion and Instrumentation in Pediatric Spinal Deformities

초록

PURPOSE : Previous data reported by the authors suggested biomechanical similarities between 4.0mm stainless steel and 4.75mm titanium single-rod anterior thoracoscopic instrumentation systems. The purpose of this study was to compare clinical and radiographic outcomes between these two instrumentation systems in patients with at least 2 years of follow-up. MATERIALS AND METHODS : 75 anterior thoracoscopic fusion and instrumentation cases were performed by a single surgeon for correction of a right thoracic curve. The first 34 cases used 4.0mm stainless steel and subsequent cases used 4.75mm titanium constructs. The first 10 stainless steel cases and the first 5 titanium cases were eliminated to account for a potential learning curve effect. A minimum 2-year follow-up requirement eliminated the most recent 11 titanium cases. The stainless steel group (n=24) underwent surgery from 2000-2001 and the titanium group (n=25) underwent surgery from 2002-2004. Demographic, operative, and radiographic data were compared between the patient groups. An assessment of intervertebral fusion using a rating system of 1-4 (1 indicated solid fusion and 4 indicated pseudoarthrosis) was performed using radiographs at the most recent follow-up. A p value of 0.005 was considered significant. RESULTS : The mean age at surgery, gender ratio, length of hospitalization, estimated blood loss, and operative time were not statistically different between the two patient groups (p>0.06). The average length of radiographic follow-up for the stainless steel group was 4.03 years (range 1.85-6.15 years) compared to 2.36 years (range 1.94-4.94 years) for the titanium group (p=0.001). Pre-operative and > 2-year post-operative coronal Cobb angle measurements were similar between the patient groups (p>0.03). The quality of intervertebral fusion was not significantly different between the groups (p=.404). However, 1 of 2 patients in the stainless steel group required surgical revision with posterior